The purpose of this studies was to construct a simplified survey system and the practical use for sediment disaster such as bank erosion, soil avalanche and debris-avalanche occured in a limited mountainous area. To grasp the situation and scale of a disaster, we had chosen the way of taking photograph and video imageryby optical camera and televisonal camera (TV camera) from a very low altitude after general cosideration on the target area. A improved remote control helicopter for industries was selected as a practical platform loaded the survey system through the investigation into structural condition and legal controls requi-red to satisfy as the platform for this purpose. One pre-flight at Yamatotakada for arrangments and two test-flights at Mayuy-ama in Shimabara has been put into practice. Developed system was broadly dividedinto two parts, the one was the loaded part composed with 35 mm camera or a 60 mm camera, wireless monitoring compact TV camera, two wireless compact TV cam
… Moreeras for stereoscopic vision and mechanism for operation, and the other was a part on the ground composed with receiving and recording equipment for TV imagery and transmitters for mechanical control except for controling a RC helicopter.Taken aerial photograph and recorded video imagery were investigated from viewpoints of effectiveness for grasping disaster situation and operating RC helicopter. Two contour maps before and after debris-avalanche with a scale of 1 to 500 were drawn together with longitudinal section and latenal profile by using acrial photogramtry. Furthermore, several three dimensional imageries were also produced through a system for stereo imagery analysis in a personal computer. As the results of this studies, it had beet become clear that stereoscopic vision on the spot was effective for improvement of RC helicopter opertation, replay of stereo imagery anytime and anywhere was very effective to understand phenomena and situation, change of stream bed by debris-avalanche could be well expressed in the outcome with large scale laerial photogramtry, three dimensional imageries processed in a personal computer were effective to grasp situation and to extract change and so on. From these matters the usefulness of this survy system a avery low latitude could be pointed out specifically. Less